Modern Ethernet is based on the principle of using 4 twisted pairs inside a single cable jacket. The twist is clearly visible when physically inspecting the pairs inside the cable. What is the significance of twisting pairs? It is done to prevent a phenomenon known as ‘cross-talk’ which is essentially the occurrence of electromagnetic interference across the line. Each pair uses a different twist rate per meter which further facilitates noise rejection.
Cables are split into different categories commonly known as a CAT rating. This identifies cable characteristics such as twist rate, wire thickness, anti-crosstalk properties and shielding. Most importantly it defines the overall bandwidth capability on each category which takes all factors into account. In order to improve bandwidth capacity for each cable type, you will generally need to increase wire thickness and use a higher twist ratio per pair. This means that as the cable capacity specification improves, it also becomes more rigid, making it more difficult to install.
Although possible, we generally don’t recommend that cable runs exceed more than 100m, as speeds become unpredictable beyond this point. Let’s take a look at some of the most common cable categories available.
CAT6 Ethernet Cable
If we look at CAT6, it is capable of 1Gbps+ speeds at 100m, and even 10Gbps at up to 55m. It uses 250MHz of bandwidth to achieve this speed and is a good choice for new installations. However, its increased cable thickness requires a bit more skill to install and the RJ45 connectors are not as easy to crimp as with CAT5e. It's also worth mentioning that you should never use CAT5e RJ45 connectors on CAT6 cable.
CAT6a Ethernet Cable
Next, we have CAT6a which offers an even greater transmission speed at 10Gbps for runs up to to 100m for 500MHz of bandwidth. These cables should be used in high capacity LAN’s with 10G switching environments. It’s more challenging to install and makes use of RJ45-CAT6a connectors which again are not compatible with other cable types.
